Scenario A — Party can. Load the preset (355 ml, fridge → 6°C). Scrub to halfway: the drink is cooler than room but not yet “ready.” Env ≠ ready in one glance.
Scenario B — Freezer rush. Same can, freezer method. Minutes to target shrink; freeze margin appears. If guests are late, the curve keeps falling toward −18°C — set a timer at the target crossing. A margin under ~15 minutes is a planning yellow light, not a dare.
Compare freezer vs ice bath on the same volume: bath often matches speed with a safer 0°C asymptote.
Scenario C — Wine fridge. 750 ml glass toward 12°C. Larger τ, gentler target above fridge asymptote — no freeze drama, just patience. Glass containers stretch τ versus cans on the same method.
Scenario D — Impossible target. Set fridge method and a target below 4°C. The panel refuses a fake time: you cannot beat the asymptote. That refusal is the framing — Env ≠ ready includes “not reachable here.”
Scenario E — Unit flip for hosts. Switch °C ↔ °F on the same scene. Minutes to ready should stay consistent; only the displayed temperatures remap. Pair with the temperature converter if you only need a one-off conversion without a cooling curve.